A new loss-reduced distributed amplifier structure

A novel loss-reduced distributed amplifier (DA), branched distributed amplifier (BDA), is presented. Unlike conventional DAs, in this structure the source/load is connected at the middle of input/output transmission lines. This technique effectively reduces the length of transmission lines and in turn lowers signal attenuation. Moreover, the optimal number of stages can be increased in the proposed structure. The final amplifier is implemented in 0.13 mum IBM´s CMRF8SF CMOS as two cascaded DAs with different number of stages. Post-layout simulation results show a 3-dB bandwidth of 38.5 GHz and an average pass-band gain of 20.5 dB, resulting in a gainbandwidth (GBW) product of 408 GHz. Input matching is less than -20 dB and output matching is well below -10 dB over the entire bandwidth. The chip area is 1.2 mm by 0.6 mm and power consumption is 154 mW.